A conveyor of this kind, in which two parallel endless chains, spaced apart and joined together by cross struts to form a chain system, are driven by chain wheels, and including a distributor for items being conveyed that has followers engaging in guide rails and is forcibly displaced transverse to the conveying direction while the chains are circulating, is disclosed in the brochure "STEWART HORIZONTAL SWITCHES" of the firm STEWART SYSTEMS, PLANO, TEX. It is used on very long conveying runs, e.g. up to 100 m or more in length, such as are to be found at airports or main post offices as distributing stations for packets, items of luggage or similar objects. The conveyor runs, which often comprise endlessly circulating strips of stainless steel as conveyor belts, include these positioning conveyors to divert the conveyed goods either to the left or to the right in order to effect purposive sorting, e.g. in the case of parcels sorting oriented according to the addressee. Before the item to be conveyed --for example said parcel--arrives on the positioning conveyor on the incoming end its destination is determined by means of a reading device and a switch inserted at the incoming end ahead of the multitrack guide rails that branch or fork in the conveying direction is automatically adjusted. Since the followers of the distributor, which is about half as wide as the conveyor and is made up of diverter plates, are in engagement with the switch which, like the guide rails is, for example, U-shaped, they are guided to one of the rail tracks when the switch pivots horizontally. In the case of guide rails that fork and branch into two tracks they are thus guided either into the track leading to the right or that leading to the left side of the conveyor, so that the parcel resting on the diverter plates is also correspondingly distributed either to the left or to the right. The article being conveyed always runs on the positioning conveyor at a sufficient distance from the following item.
The known positioning conveyors and conveyed article distributors are subjected to severe vibrations, only allow low transporting speeds of at most 60 m/min, and in addition generate a great deal of noise. Furthermore the service or operating life is impaired by the heavy impacts that cause the noise and occur when the diverter plates are turned round and transversely displaced. This is due on the one hand to the fact that as the diverter plates are turned at the turning points of the conveyor they overlap with a jump, since for fairly stable running conditions they are twice as wide as the pitch of the cross-struts, which are in the form of round bars. On the other hand it is impossible to avoid severe impacts when the followers, which e.g. project downwards and have plates with rollers at their ends, reach the fork where the guide rails divide to continue in the direction of transport as multiple tracks and are there abruptly forced to run in another direction. The parcels to be sorted are thereby greatly accelerated, which both impairs their alignment and leads to damage to the packaging. Finally the chain wheel drive of the known conveyor is not only prone to intense vibration but also suffers a disadvantageous polygon effect, i.e. the chain wheels twist repeatedly. Since there are altogether four chain wheels round which the chains pass at the incoming and outgoing ends, the chains lose their engagement with the chain wheels or their guides at many points; vibration is therefore unavoidable.